AAIB: "The engines did not shut down and both engines continued to produce thrust at an engine speed above flight idle, but less than the commanded thrust."
It is interesting that on this topic the latest report essentially repeats the information released earlier and gives no new details about the behaviour of the engines. Was the rpm steady, decreasing or increasing, were there any minor or major surges, did the engines behave identically?
This kind of details may give some clues as to the nature of the fault. For example, I'd expect the signs of a fuel flow impairment to be different than those of a fuel contamination.
My interpretation of this is that the AAIB will use the detail data to simulate any possible fault sources, but wants to do so in peace from any media speculations. And that's OK for me. We'll see the outcome sooner or later.